PROJECT SUMMARY/ABSTRACT Chronic and acute consumption of alcohol are associated with alterations in autonomic nervous system (ANS) activity. Acute alcohol consumption leads to an immediate increase in heart rate and blood pressure and a reduction in vagal tone. Chronic heavy drinking in the context of Alcohol Use Disorder (AUD), is also associated with tonically elevated heart rate even when sober. Acute alcohol intoxication and AUD are also associated with dramatically disturbed sleep with common findings including increased wakefulness and likelihood of brief arousals throughout the night in AUD and in the second half of the night following drinking prior to sleep. Sleep should be a cardio-protective state with lower heart rate (HR) and blood pressure (BP) than wakefulness. Sleep disturbance is a known risk factor for the development of cardiovascular disease (CVD) with sleep deprivation and common sleep disorders being associated with increased cardiovascular morbidity and mortality. Indeed it has been argued that sleep disturbance may be the most important, potentially modifiable, cardiovascular risk factor. NIAAA has established guidelines that indicate that up to four drinks per day (maximum of fourteen drinks per week) for men and three drinks per day (maximum of seven drinks per week) for women are considered as low risk, yet little is known of the impact of this level of drinking on sleep and ANS function. This exploratory/developmental grant proposal will evaluate sleep, sleep EEG and state of the art measures of ANS and CV function during sleep under sober, and recommended safe drinking conditions.